The use of preoiling devices and oil reservoirs or accumulators of various designs in conjunction with internal combustion engines is generally well known. It has long been an acknowledged fact that a great deal of engine wear occurs as a result of "cold start scuffing," i.e., the starting of an engine after it has been idle for a period of time sufficient to allow its lubricating oil to drain into the engine's oil pan and crankcase, thus leaving many vital engine parts with no lubricant protection until the engine has been started and the oil pressure brought up to an acceptable level by the oil pump. Various preoiling devices have been designed, all having the purpose of providing oil pressure to the engine prior to start-up. An internal combustion engine preoiling device is discussed, e.g., in my U.S. Pat. No. 4,094,293 issued June 13, 1978.
My co-pending U.S. patent application Ser. No. 557,397 filed Dec. 2, 1983, which is a continuation-in-part of application Ser. No. 331,371 filed Dec. 16, 1981 entitled "Improved Engine Prelubricator and Pressurized Lubricant Reservoir" discloses that pressurized lubricant may be stored in a reservoir and be used to lubricate the center bearing of an exhaust-driven turbocharger after an engine is shut down.
Exhaust-driven turbochargers are themselves well known in the automotive arts. The idle speed of an exhaust-driven turbocharger often exceeds 30,000 rpm with top speeds of 90,000 to 120,000 rpm. When the automobile engine is operating, lubrication is supplied to the turbocharger's center bearing by the engine's lubrication system. When the engine shuts down, the flow of oil to the turbocharger center bearing essentially ceases. A time period of about 20 to 30 seconds can elapse between the time that the engine shuts down and the time at which the turbocharger stops turning. During this time period, the center bearing temperature can increase to as high as 1200.degree. F. At such high temperatures, and because of the lack of oil flow, the small amount of oil remaining in the turbocharger center bearing carbonizes and ultimately the bearing will fail as a result of galling or seizure.
Engine prelubrication assemblies and exhaust-driven turbocharger center bearing post engine shut down lubrication systems have the following common feature. Lubricant is stored in a reservoir under pressure. When the machinery requires lubrication, the pressurized lubricant stored in the reservoir is used to lubricate the machinery. The source of pressurized lubricant stored under pressure in the reservoir of both such systems is the lubrication system of the internal combustion engine. That is, in both such systems the reservoir is charged with pressurized lubricant from the lubrication system of an internal combustion engine.
It will be appreciated, that when an engine is initially started up, it would be undesirable for the engine lubrication system to recharge the reservoir of these systems with pressurized lubricant from the engine lubrication system after a major volume of oil has been spent for pre-oiling. At engine start-up and during the build-up of lubricant pressure by the engine's lubricant pump, the engine lubricant system should be dedicated to providing lubricant to the engine parts and associated systems.
Recharging of the reservoir with lubricant from the engine lubrication system after initial engine start-up is not generally a problem if automatically actuated control valves are used to selectively control the flow of lubricant to and from the reservoir. An automatic solenoid actuated control valve for use with an engine prelubricator assembly is disclosed in my U.S. Pat. No. 4,094,293. An automatic solenoid actuated control valve for use with an exhaust-driven turbocharger center bearing post engine shut down lubrication system is disclosed in my co-pending U.S. patent application Ser. No. 557,321 filed Dec. 2, 1983 entitled "Pressurized Lubrication Assembly for the Center Bearing of a Turbocharger."
One may choose to use a manually operated control valve for controlling the flow of lubricant to and from the reservoir in either an engine prelubricator assembly or an exhaust-driven turbocharger center bearing post-engine shut down lubrication system. As disclosed in my aforementioned co-pending application entitled "Improved Engine Prelubricator and Pressurized Lubricant Reservoir" an exhaust-driven turbocharger center bearing post-engine shut down lubrication system may operate satisfactorily without any valve for controlling the flow of lubricant to and from the reservoir.
In either system, when an automatically controlled valve is not used for regulating the flow of lubricant from and to the reservoir, problems may arise from the recharging of the reservoir with lubricant at the time of initial engine start-up. These problems can arise from system design, inherently slow operator manual reaction time, and/or operator error.
There is also a need in the art for improved manually operated valves for use with engine prelubricator assemblies and exhaust-driven turbocharger post-engine shut down lubrication systems.